Born the son of Antoine Charles Lemaire and Marie Jeanne Davio, he had an excellent early education, and acquired the reputation of being an outstanding scholar.
At some stage his botanical interest was sparked and developed by his association with M. Neumann, horticulturist at the Museum of Natural History.
[1] He worked for some time as an assistant to M. Mathieu, at a nursery in Paris, building up a collection of Cactaceae, a group to which he would devote almost all of his life.
In 1854 he turned to editing L'Illustration Horticole, also in Ghent and owned by Ambroise Verschaffelt, and stayed there until 1870 when he returned to Paris where he died in June 1871.
Édouard André (1840–1911), who succeeded him as editor of L'Illustration Horticole, felt that "Posterity will esteem M. Lemaire more highly than did his contemporaries.